V1 Josh's City Goblin - 10 XFE Donor

[Desert Sasqwatch]

To me, that log graph doesn't look like anything out of the ordinary. The coolant temp came up to a good operating temperature - about 215F from what I can discern - and really didn't track up or down much during the time charted. Not certain if your expecting to see sudden rises or falls in the temperature? Water/liquid mass takes time to warm or cool - reason that a 'watched pot never boils' saying - and will not show rapid changes.

The thermostat is used to help regulate the coolant into the optimum operating temperature, it will open more if hotter, close more if cooler. What temperature is the thermostat? I believe the stock Cobalt is 195-205 range. The coolant will stabilize typically about 10-12 degrees above the opening temperature - that is what I'm seeing from the graph.

 

[jirwin]

Not sure. Whatever stock is. It runs 185 usually. The problem is, if I beat on it a little more, it'll get 240F plus. I realize that engines get hot, but this is new-ish. Since about the time in switched to E85. Its never acted like this before.

 

[jirwin]

Maybe it just comes with the territory of making good power. Idk

 

[Desert Sasqwatch]

Fresh engines will run a little hotter until everything is seated and there will be a small reduction in friction. E85 does burn hotter than gas - relatively speaking - in that more fuel is used during combustion. Good for keeping the incoming charge cooler, but also creates more heat when ignited. That heat will be dissipated into the engine internals and block and is likely the cause of your seeing somewhat higher temperatures than you saw before switching to E85.

I would recommend getting a 185F thermostat and installing it to see if it makes a difference - maybe?

 

[jirwin]

RockAuto seems to think its a 180F tstat (looking at GM Genuine)

 

[Gtstorey]

What are the ambient temps when it gets to 240?

When you say it still had pressure when cool, is that a little hiss or puking real amounts of coolant!

 

[jirwin]

What are the ambient temps when it gets to 240?

When you say it still had pressure when cool, is that a little hiss or puking real amounts of coolant!

70F. It went from a half full coolant res to full and then pissed coolant everywhere. I left the res full expecting to have to fill.it during thayndrove, but it just went down to about a third full.

 

[Dsteinhorst]

The only time I see my coolant temp above 200 degrees is when idling standing still. Even when getting on it quite a bit, it rarely goes above 190 degrees. I still have the stock thermostat.

This is seemingly a lot like a headgasket leak.

Also, I'm super jealous you get 15 PSI. I'm at 11 PSI on a 2.9 pulley.

 

[jirwin]

The only time I see my coolant temp above 200 degrees is when idling standing still. Even when getting on it quite a bit, it rarely goes above 190 degrees. I still have the stock thermostat.

This is seemingly a lot like a headgasket leak.

Also, I'm super jealous you get 15 PSI. I'm at 11 PSI on a 2.9 pulley.

That's how mine was too prior to E85. Given the timing I'm not super bummed out since its nearing end of season up north here, but I would like to get it figured out if I can. I'm running a thick Cometic headgasket to lower compression for boost, but now that I've decided to stay supercharged, if I have to replace it, I'll replace it with something much thinner, getting me upwards of 10.5:1 compression.

 

[Gtstorey]

My best guess would be head gasket but you might want to confirm the temp sensor is reading correctly. But that doesn’t really explain the excessive pressure build up after cooling.

 

[jirwin]

My best guess would be head gasket but you might want to confirm the temp sensor is reading correctly. But that doesn’t really explain the excessive pressure build up after cooling.

Yeah, the only thing that explains that is a head gasket leak in my mind.

I also wonder about the height of everything. That line going from above the inlet on the head to little nipple on top of the coolant res seems to be... the same height? Idk. I've thought about raising the coolant res up an inch or two if possible to rule any backfeeding out. But again, doesn't explain the pressure.

I'll check the coolant pressure again tomorrow morning after it cools overnight

 

[Mahkoi]

This may help figure it out. Relatively cheap and if the test fluid changes color you know you have combustion gasses in your coolant.

Block Tester BT-500 Combustion Leak Test Kit - Made in USA https://a.co/d/0xNsog9

 

[jirwin]

This may help figure it out. Relatively cheap and if the test fluid changes color you know you have combustion gasses in your coolant.

Block Tester BT-500 Combustion Leak Test Kit - Made in USA https://a.co/d/0xNsog9

Funny, I was actuallynjust looking at this

 

[Mahkoi]

Funny, I was actuallynjust looking at this

I haven't used one in a long time but it was kinda neat to watch to watch the fluid turn yellow and confirm my suspicions then have the customer decline repairs and tell me "I'll just take the oil change"

 

[jirwin]

So this morning I opened the cap and there was a wooshing sound. Couldn't tell if it was in or out, but I think out because the coolant level rose. I had the cap off before my drive last night (cold).

So, hypothetical scenario to see if I'm understanding things correctly. The cooling system is closed loop. Barring a leak, it will only lose pressure if the pressure goes over 15PSI and the cap vents. I open the coolant res and fill it to the cold fill line. I run the car. I let it cool off over night. The res should be back to the same level, and I should be able to open the cap and have no air go in or out (assuming same ambient temperature).

Is that right?

 

[Gtstorey]

A closed loop system shouldn't change volume. It's either pulling air in as it heats up (I can't think of a real scenario that would cause this) or it's adding combustion gas to the system causing it to pressurize. This pressure causes the non ridged parts of the system (hoses mostly, maybe the radiator a little) to expand slightly. This allows the coolant level to drop as the volume increases. Release the pressure and everything returns to it's original size and coolant rises.

What happens on a drive that gets it to temp but doesn't get to significant boost?

 

[Gtstorey]

I haven't used one in a long time but it was kinda neat to watch to watch the fluid turn yellow and confirm my suspicions then have the customer decline repairs and tell me "I'll just take the oil change"

I have heard these don't work as well on a remote reservoir system as directly from a radiator but no personal experience either way. If this is is just lifting the head under boost, it also might be difficult to get a good reading.

 

[jirwin]

What happens on a drive that gets it to temp but doesn't get to significant boost?

Good idea. I'll try that tonight. I could just let it idle up to temp (and leave it for a few minutes) to ensure I'm not getting any boost at all, no?

 

[Gtstorey]

Good idea. I'll try that tonight. I could just let it idle up to temp (and leave it for a few minutes) to ensure I'm not getting any boost at all, no?

Maybe, but it might be hard to get a real idea on what is going on since any exchange might be minimal.

 

[Joebob]

I am following for several reasons.

1. I am adding a supercharger to my 2.4 auto goblin so I am trying to learn from you
2. I am learning HP tuners so again trying to learn from you the changes from NA to SC engine management
3. your problems might become mine as well so I hope all your problems get a solution.

To answer your question, yes that sounds right. any coolant temp increase will increase it's volume and therefor pressure in a closed loop. Any high temp of coolant causing to vaporize coolant should vent out of the cap for anything over 15 psi. Upon cooling the vapor condenses and coolant "shrinks" and the pressure and volume should return to normal except the liquid volume lost during venting.

I have seen classic cars with collapsed radiator hoses when upon cooling, the radiator cap did not let cool overflow tank coolant back into the closed loop system. We have a pressurized expansion tank that I guess should let air in in a vacuum situation.

To have cold air keep the system pressurized means that gas is being injected into the system and I agree a head gasket under boost might be causing it.

In looking at the temperature, the amount of injected gas into the coolant should not cause such a rapid and large temperature increase as gas does not have a lot of heat capacity.

What I do see are a few things of concern in your short log:
1. It looks like the high temp increase correlates to a period where you have a very high spark advance of 50 degrees. that could cause an increase in engine and coolant temps.
2. The temp rise is under relatively slow speeds and maybe that is at the critical speed where excessive engine heat meets low natural airflow. (Can you confirm the fan is working as your PID states 0 percent?). The temp seem to cool off rapidly under sustained coasting and lower spark advance.
3. You have various misfires on your engine which could be plug/coil/injector issues. This would read as lean by the O2 sensors and add extra fuel which messes up the fuel mapping
4. Your control module voltage drops pretty low <11.6V at times and gets no higher than 12.4V or so. It looks like you could have a ground or charging issue which mess up any number of things such as fan speed, injector offset calibrations, or coil voltages to the plugs.

You goblin looks to be making crazy power by the torque/Mass airflow number (double of my N/A). I hope you find its ills.

Joe